NEW YORK, NY  [Wednesday Jul.12.2006]  /Mix103FM.com/ -- Rihanna's got plenty to be "happy" about.

The singer has scored a major hit with her single "S.O.S." and, earlier this month, she kicked off her first-ever headlining tour in support of her latest album "A Girl Like Me."

But Rihanna is also smiling because she's just signed on to be part of a new ad campaign for cosmetic company Clinique's Happy fragrance.

According to MTV.com, the Clinque "Happy" campaign is set to launch in December, and Rihanna will be heard singing a new song called "Just Be Happy," written by her friend and "Unfaithful" duet partner, Ne-Yo.

Country singer Julie Roberts will also record a version of "Just Be Happy" for the Clinique ads.

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